Anti-fog coating

ABSTRACT

The present invention relates to an optical component having a crosslinked anti-fog coating obtainable by covalent attachment of a silane derivative of the formula (2) to the surface of the optical component and crosslinking of adjacent molecules: 
       R o X m SiB n   (2)
 
     wherein 
     m=1 to 3, n=1 or 2 and o=0 or 1, with the proviso that m+n+o =4; 
     the radical X is selected from halogen or C 1-4 -alkoxy, and 
     for m=2 or 3 the individual radicals X may be identical or different, 
     the radical R is C 1-4 -alkyl, 
     the radical B has the structure -B1-B2, in which -B2 is a terminal hydrophilic group which is crosslinked to at least one hydrophilic group of an adjacent molecule of the anti-fog coat, and -B1- represents either a spacer group, which joins the hydrophilic group B2 to the Si atom, or a covalent bond, 
     where the terminal hydrophilic group -B2 is poly(meth)acrylate, and for n=2 the individual radicals B may be identical or different.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority of German patent application no. 102012 009 691.7, filed May 15, 2012, the entire content of which isincorporated herein by reference. This application is a divisionalapplication based on U.S. application Ser. No. 13/893,021, filed May 13,2013, the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an anti-fog coating on an opticalcomponent and also to a method for its production.

BACKGROUND OF THE INVENTION

Present-day eyewear lenses (corrective spectacles, sunglasses,ski/sports eyewear, protective goggles) mist up under adverseconditions. These conditions are, on the one hand, the transition from acold environment into a warm environment (for example, entering the homefrom outside in cold temperatures in the winter, or leaving anair-conditioned building in a country with tropical climate conditions),and on the other hand if the eyewear lens makes contact with a source ofwarm/hot air with high relative humidity. Once the eyewear has mistedup, the wearer must typically take off his or her eyewear and eitherwait until the misting disappears or else remove the misting by wipingwith a cloth.

The problem of misting affects optical components in general.

If the misting is looked at under a light microscope, it is observedthat the “mist” consists of small droplets of water. These droplets havea diameter of typically 20 μm. The degree of surface occupation by thesedroplets is approximately 50%, as also predicted by models of kinetictheory. The reason why a misted lens appears milky is that the dropletsdisrupt the propagation of light.

The reduction in transmission is accompanied by an increase in thescattered light fraction, causing the glass to appear milky. A lowcontact angle of the water droplets is advantageous, since transmissionis then high and the scattered light fraction low.

Given that, under the conditions under which lenses mist up, it is notpossible to prevent the condensation of water, one approach at asolution is to treat the surface in such a way that the water drops forma small contact angle with the surface.

Approaches exist for how this can be implemented for optical lenses suchas eyewear lenses, for example. These approaches typically involvesprays or liquid-impregnated cloths. The liquids employed in thiscontext are from the group of the hydrophilic surfactants. There is amultiplicity of such products on the market. A phenomenon common tothese products is that the anti-mist effect or anti-fog effect is notlong-lasting, and it is instead necessary to apply the solutionregularly to the surface. There are also approaches which harnessphysical effects to prevent the development of water drops, examplesbeing venting systems in ski goggles.

There are also solutions for optical lenses such as eyewear lenses whichare provided with a hard coating and which ensure a long-lastinganti-mist (anti-fog) effect.

Present-day high-grade optical lenses such as, for example, high-endeyewear lenses are normally provided with an anti-reflection (AR)coating. This coating reduces unwanted and annoying reflections.

There is advantage in managing to modify the surface of AR-coatedoptical components, such as eyewear lenses, in such a way that along-lasting anti-mist effect or anti-fog effect is obtained, hencedispensing with the need for regular aftertreatment, with a spray, forexample. Particular attention in this context is to be placed onmaintaining the optical effect of the anti-reflection coat.

SUMMARY OF THE INVENTION

In accordance with a first aspect, this object is achieved through theprovision of an optical component having an anti-fog or anti-mistcoating obtainable by covalent attachment of a silane derivative of theformula (1) to the surface of the optical component:

R_(o)X_(m)SiA_(n)  (1)

where

m=1-3, n=1-2 and o=0-1, with the proviso that m+n+o=4;

the radical X is selected from halogen or C₁₋₄-alkoxy, and for m=2-3 theindividual radicals X may be identical or different,

the radical R is C₁₋₄alkyl,

the radical A has the structure -A1 -A2, in which -A1 - is a hydrophobicgroup bonded to the Si atom, and A2 represents a terminal hydrophilicgroup bonded to the hydrophobic group A1,

the hydrophobic group -A1- being selected from -arylene-; alkylene-;-C₁₋₆alkylene-arylene-; -arylene-C₁₋₆alkylene-;-C₁₋₆alkylene-arylene-C₁₋₆alkylene-; -poly(C₃₋₆alkoxylene)-, fluorinatedor perfluorinated-alkylene-, fluorinated or perfluorinated-poly(C₂₋₆alkoxylene)-, or a combination of these groups,

and the terminal hydrophilic group -A2 is selected from polyethoxyl,poly(meth)acrylate, sulphonic acid or a salt thereof, sulphonic ester,or a combination of these groups,

and for n=2 the individual radicals A may be identical or different.

The covalent attachment of the compound of the formula (1) to thesurface of the optical component is accomplished by reacting at leastone of the reactive, hydrolyzable —Si—X— groups with a suitable reactivesurface group (e.g. an —OH group) to form —Si—O—. This type of surfaceattachment of a silicon compound having a reactive, hydrolyzable groupis known in principle to the skilled person.

Preferably X is methoxy, ethoxy or Cl.

In the context of the present invention it has been found that through aradical A on the Si atom with the structure -A1 -A2, which features asuitable combination of hydrophobic group -A1- and terminal hydrophilicgroup -A2, on the one hand the —Si—O— bond, via which the molecules ofthe anti-fog coating are bonded to the surface of the optical component,is shielded more effectively from water, and the stability of theanti-fog coating with respect to hydrolysis can be enhanced, and,furthermore, the contact angle of the water to the anti-fog coating iskept low.

In the context of the present invention it has also emerged that thepresence of a suitable hydrophobic group -A1- in the compound of theformula (1) significantly reduces the unwanted adsorption of thehydrophilic group -A2 on the surface of the optical component, leadingin turn to an increased occupation density of the molecules of theanti-fog coat on the surface of the optical component.

As set out above, the hydrophobic group -A1 - is selected from-arylene-; -C₁₋₆alkylene-arylene-; -arylene-C₁₋₆alkylene-;-C₁₋₆alkylene-arylene-₁₋₆alkylene-; -poly(C₃₋₆alkoxylene)-, fluorinatedor perfluorinated -alkylene-, fluorinated or perfluorinated-poly(C₃₋₆alkoxylene)-, or a combination of these groups.

From the structure -A1-A2 of the radical A it is evident that thehydrophobic group is at least divalent—that is, is joined by a covalentbond to each of the two adjacent groups. In the text below, the name ofany such divalent group carries the ending “-ene”. For example, the term“arylene” refers below to a divalent aryl group.

The arylene group -Ar- is preferably phenylene -Ph-, which may besubstituted or unsubstituted. The arylene group may optionally beconnected via a (divalent) C₁₋₆alkylene group, which is optionallyfluorinated or perfluorinated, to the Si atom and/or to the terminalhydrophilic group -A2.

An example of a suitable alkylene group is -C₁₋₁₀alkylene-.-Poly(C₃₋₆-alkoxylene)- is preferably a polypropoxylene and/orpolybutoxylene group. In the context of the present invention it hasemerged that -poly(C₃₋₆-alkoxylene)- has sufficient hydrophobicity toimprove the stability of the anti-fog coating with respect tohydrolysis. The degree of alkoxylation, i.e. the number ofC₃₋₆-alkoxylene monomer units in the poly(C₃₋₆-alkoxylene)- group, canbe varied over a wide range and is situated for example in the rangefrom 1 to 8, more preferably 2 to 8.

In the context of the present invention, a perfluorinated alkylene groupmeans an alkylene group in which all of the hydrogen atoms aresubstituted by fluorine. The number of C atoms in the fluorinated orperfluorinated alkylene group and hence the length of the group can bevaried over a wide range. The fluorinated or perfluorinated alkylenegroup is preferably a fluorinated or perfluorinated C₁₋₂₀-alkylenegroup, more preferably fluorinated or perfluorinated C₁₋₁₀-alkylene.

In the context of the present invention, a perfluorinatedpoly(C₂₋₆-alkoxylene) group means a poly(C₂₋₆-alkoxylene) group in whichall of the hydrogen atoms are substituted by fluorine. Exemplarypoly(C₂₋₆-alkoxylene) groups that can be identified are polyethoxylene,polypropoxylene or polybutoxylene. The degree of alkoxylation, i.e. thenumber of C₂₋₆-alkoxylene monomer units in the fluorinated orperfluorinated poly(C₂₋₆-alkoxylene) group, can be varied over a widerange and is situated for example in the range from 1 to 8, morepreferably 2 to 8.

As stated above, the terminal hydrophilic group -A2 is selected frompolyethoxyl, poly(meth)acrylate, sulphonic acid or a salt thereof,sulphonic ester, or a combination of these groups.

The degree of ethoxylation of the polyethoxy group can be varied over awide range and is situated for example in the range from 4 to 20.

The sulphonic ester in question is preferably the methyl or ethyl ester.

Where the hydrophilic group -A2 comprises a poly(meth)acrylate, thelatter may be constructed exclusively from identical monomer units suchas CH₂═C(CH₃)COOC₁₋₄-alkyl (e.g. CH₂═C(CH₃)COOCH₃),CH₂═C(H)COOC₁₋₄-alkyl (e.g. CH₂═C(H)COOCH₃), hydroxyethylenemethacrylate (HEMA), 2-acrylamido-2-methylpropanesulphonic acid (AMPS),trimethylolpropane triacrylate or pentaerythritol tetraacrylate, or frommixtures of these monomer units, and may alternatively also containfurther comonomer units. The poly(meth)acrylate as hydrophilic group A2may be linked for example via an ester group with the hydrophobic group-A1-.

In the context of the present invention it is possible for adjacentmolecules of the formula (1) of the anti-fog coating to be crosslinkedvia covalent bonds of the hydrophilic groups -A2, especially if -A2 ispolyethoxyl or poly(meth)acrylate. This may lead to even bettershielding of the —Si—O— bond toward water. If, however, the compound hasthe above-described structure with -A1 -A2, then this leads, evenwithout crosslinking, to enhanced stability with respect to hydrolysis.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawingswherein:

FIG. 1 shows, diagrammatically, the surface of an optical component thathas been modified with silane compounds of the formula (1) to form ananti-fog coating. In the upper compound of FIG. 1, the hydrophobic group-A1- is a -phenylene- and the terminal hydrophilic group is polyethoxy.In the lower compound of FIG. 1, the hydrophobic group -A1- is a-poly(propoxylene)- and the terminal hydrophilic group is againpolyethoxy.

FIG. 2 shows diagrammatically the surface of an optical component thathas been modified with silane compounds of the formula (1) to form ananti-fog coating. In the upper compound of FIG. 2, the hydrophobic group-A1- is a perfluorinated -poly(propoxylene)- and the terminalhydrophilic group is polyethoxy. In the lower compound of FIG. 2, thehydrophobic group -A1- is a perfluorinated -alkylene- and the terminalhydrophilic group is again polyethoxy.

FIG. 3 shows diagrammatically the surface of an optical component thathas been modified with silane compounds of the formula (1) to form ananti-fog coating. In the compound of FIG. 3 the hydrophobic group -A1-is a -phenylene- and the terminal hydrophilic group is a sulphonic acidor a sulphonic ester.

FIG. 4 shows, diagrammatically, a surface of an optical component thathas been coated with a precursor compound of the formula (₃).

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The optical component may comprise, for example, optical lenses made ofglass or plastic, or else a beam splitter component. Mention may be madeby way of example in this context of eyewear lenses, telescope lenses,cover plates or cover glasses, or else lenses such as ocular lenses,camera lenses or front lenses.

In one preferred embodiment the optical component has an anti-reflectioncoat (AR coat). The anti-fog coating may be applied directly on the ARcoat.

The coat thickness of the anti-fog coating may be varied over a widerange, for example from a monomolecular (i.e. single-layer) coat throughto a multi-layer coat with a coat thickness of up to 150 nm. Where theoptical component has an anti-reflection coat (AR coat), the coatthickness of the anti-fog coating is preferably selected so as not toimpair the function of the AR coat. Where the anti-fog coating ispresent on an AR coat, the coat thickness of the anti-fog coating ispreferably in the range from single-layer to 100 nm, more preferably inthe range from 10 nm to 20 nm.

Silane derivatives of the formula (1) are available commercially or canbe prepared via synthesis techniques known to the skilled person.

Methods for the covalent attachment of silane derivatives to reactivesurfaces are known in principle to the skilled person. According to onevariant, the silane derivative in a suitable solvent is contacted withthe surface under reactive conditions. Alternatively, the silanederivative can also be reacted with the surface via the gas phase.

According to a further aspect, the present invention relates to a methodfor producing an anti-fog coating on an optical component, comprisingthe provision of the optical component and the covalent attachment ofthe silane derivative of the formula (1) by chemical reaction withreactive groups on the surface of the optical component.

With regard to the properties of the silane derivative of the formula(1) and of the optical component, reference may be made to thestatements above.

According to a further aspect, the present invention relates to the useof the silane derivative of the formula (1) for providing an anti-fogcoating on an optical component.

According to a further aspect, the present invention relates to anoptical component having a crosslinked anti-fog coating obtainable bycovalent attachment of a silane derivative of the formula (2) to thesurface of the optical component and crosslinking of adjacent molecules:

R_(o)X_(m)SiB_(n)  (2)

where

m=1-3, n=1-2 and o=0-1, with the proviso that m+n+o=4;

the radical X is selected from halogen or C₁₋₄-alkoxy, and for m=2-3 theindividual radicals X may be identical or different,

the radical R is C₁₋₄alkyl,

the radical B has the structure -B1-B2, in which -B2 is a terminalhydrophilic group which is crosslinked to at least one hydrophilic groupof an adjacent molecule of the anti-fog coat, and -B1- represents eithera spacer group, which joins the hydrophilic group B2 to the Si atom, ora covalent bond,

where the terminal hydrophilic group -B2 is selected from polyethoxy,poly(meth)acrylate, sulphonic acid or a salt thereof, sulphonic ester,or a combination of these groups,

and for n=2 the individual radicals B may be identical or different.

The covalent attachment of the compound of the formula (2) to thesurface of the optical component is accomplished by reacting at leastone of the reactive, hydrolyzable —Si—X— groups with a suitable reactivesurface group (e.g. an —OH group) to form —Si—O—. This type of surfaceattachment of a silicon compound having a reactive, hydrolyzable groupis known in principle to the skilled person.

In the context of the present invention it has been found that throughthe selection of suitable hydrophilic groups in the silane derivative offormula (2) and the crosslinking of adjacent molecules in the anti-fogcoating, on the one hand the —Si—O—bond, via which the molecules of theanti-fog coating are bonded to the surface of the optical component, isshielded more effectively from water, and the stability of the anti-fogcoating with respect to hydrolysis can be enhanced, and, furthermore,the contact angle of the water to the anti-fog coating is kept low.

In the context of the present invention it has also emerged that thecrosslinked anti-fog of the invention significantly reduces the unwantedadsorption of the hydrophilic group -B2 on the surface of the opticalcomponent, leading in turn to an increased occupation density of themolecules of the anti-fog coat on the surface of the optical component.

As stated above, the terminal hydrophilic group -B2 is selected frompolyethoxy, poly(meth)acrylate, sulphonic acid or a salt thereof,sulphonic ester, or a combination of these groups.

With regard to the properties of these hydrophilic groups, reference maybe made to the above statements concerning the description of the silanederivative (1).

The degree of ethoxylation of the polyethoxy group can be varied over awide range and is situated for example in the range from 4 to 20.

Where the hydrophilic group -B2 comprises a poly(meth)acrylate, thelatter may be constructed exclusively from identical monomer units suchas CH₂═C(CH₃)COOC₁₋₄-alkyl (e.g. CH₂′C(CH₃)COOCH₃),CH₂═C(H)COOC₁₋₄-alkyl (e.g. CH₂═C(H)COOCH₃), hydroxyethylenemethacrylate (HEMA), 2-acrylamido-2-methylpropanesulphonic acid (AMPS),trimethylolpropane triacrylate or pentaerythritol tetraacrylate, or froma mixture of these monomer units, and may hydrophilic group B2 may belinked for example via an ester group with the spacer group -B1- or theSi atom.

The sulphonic ester in question is preferably the methyl or ethyl ester.

In the context of the present invention the spacer group where present,may be varied to a broad extent. A suitable spacer group, for example,is an alkylene group such as C₁₋₈alkylene, more preferably C₁₋₃alkylene.

Silane derivatives of the formula (2) are available commercially or canbe prepared via synthesis techniques known to the skilled person.

Methods for the covalent attachment of silane derivatives to reactivesurfaces are known in principle to the skilled person. According to onevariant, the silane derivative in a suitable solvent is contacted withthe surface under reactive conditions. Alternatively, the silanederivative can also be reacted with the surface via the gas phase.

According to a further aspect, the present invention relates to a methodfor producing a crosslinked anti-fog coating on an optical component,comprising the provision of the optical component and the covalentattachment of the silane derivative of the formula (2) by chemicalreaction with reactive groups on the surface of the optical component,followed by the crosslinking of the hydrophilic groups -B2 of adjacentmolecules of the anti-fog coating.

Suitable reaction conditions for the crosslinking of adjacent moleculeshaving suitable reactive groups are known to the skilled person. Wherethe crosslinking takes place via a radical reaction, it is possible touse radical initiators such as dichlorodicyanoquinone (DDQ), forexample. With certain groups, crosslinking may also be initiated byexposure to UV radiation.

With regard to the properties of the silane derivative of the formula(2) and of the optical component, reference may be made to thestatements above.

According to a further aspect, the present invention relates to the useof the silane derivative of the formula (2) for providing an anti-fogcoating on an optical component.

In the context of the present invention it is also possible to producethe crosslinked anti-fog coating on the optical component by firstcovalently bonding a suitable precursor compound for the silanederivative of the formula (2) on the surface of the optical component,this precursor compound having a terminal group with suitablefunctionality and thus allowing subsequent chemical reaction withsuitable reactants to give the silane derivative of the formula (2).

In accordance with a further aspect, the present invention relates to amethod for producing a crosslinked anti-fog coating on an opticalcomponent, where first a precursor compound of the formula (3) is bondedcovalently to the surface of the optical component:

R_(o)X_(m)SiC_(n)  (3)

where

m=1-3, n=1-2 and o=0-1, with the proviso that m+n+o=4,

the radical X is selected from halogen or C14-alkoxy, and for m=2-3 theindividual radicals X may be identical or different,

the radical R is C₁₋₄alkyl,

the radical C has the structure -C1-C2, in which -C2 is a terminal grouphaving a (meth)acrylate functionality and -C1- represents either aspacer group, which corresponds to the above-described spacer group-B1-, or a covalent bond, and the terminal group C2 is reacted with(meth)acrylate monomers to give a hydrophilic poly(meth)acrylate group,followed by the crosslinking of the

Examples of (meth)acrylate monomers that may be identified as suitablemonomers are CH₂═C(CH₃)COOC₁₋₄-alkyl (e.g. CH₂═C(CH₃)COOCH₃),CH₂═C(H)COOC₁₋₄alkyl (e.g. CH₂═C(H)COOCH₃), hydroxyethylene methacrylate(HEMA), 2-acrylamido-2-methylpropanesulphonic acid (AMPS),trimethylolpropane triacrylate or pentaerythritol tetraacrylate ormixtures thereof.

FIG. 4 shows, diagrammatically, a surface of an optical component thathas been coated with a precursor compound (3). The terminal group of theprecursor compound has a (meth)acrylate functionality, which allows thereaction with further (meth)acrylate monomers and hence the constructionof a hydrophilic poly(meth)acrylate group.

In the following further embodiments of the invention are described.

EMBODIMENT 1

An optical component having an anti-fog coating obtainable by covalentattachment of a silane derivative of the formula (1) to the surface ofthe optical component:

R_(o)X_(m)SiA_(n)  (1)

wherein

m=1 to 3, n=1 or 2 and o=0 or 1, with the proviso that m+n+o=4;

the radical X is selected from halogen or C₁₋₄-alkoxy, and for m=2 or 3the individual radicals X may be identical or different,

the radical R is C₁₋₄alkyl,

the radical A has the structure -A1-A2, in which -A1- is a hydrophobicgroup bonded to the Si atom, and -A2 represents a terminal hydrophilicgroup bonded to the hydrophobic group A1,

the hydrophobic group -A1- being selected from -arylene-;-C₁₋₆-alkylene-arylene-; -arylene-C₁₋₆-alkylene-;-C₁₋₆-alkylene-arylene-C₁₋₆-alkylene-; -poly(C₃₋₆-alkoxylene)-,fluorinated or perfluorinated -alkylene-, fluorinated or perfluorinated-poly(C₂₋₆-alkoxylene)-, or a combination of these groups,

and the terminal hydrophilic group -A2 is poly(meth)acrylate,

and for n=2 the individual radicals A may be identical or different,

and where the poly(meth)acrylate of the terminal hydrophilic group -A2comprises monomer units which are selected from CH₂═C(CH₃)COOC₁₋₄-alkyl,CH₂═C(H)COOC₁₋₄-alkyl, hydroxyethylene methacrylate,2-acrylamido-2-methylpropanesulphonic acid, trimethylolpropanetriacrylate and pentaerythritol tetraacrylate or mixtures thereof.

EMBODIMENT 2

The optical component according to Embodiment 1, where the anti-fogcoating has no crosslinking between hydrophilic groups -A2 and/orhydrophobic groups -A1- of adjacent molecules.

EMBODIMENT 3

The optical component according to Embodiment 1, where the anti-fogcoating has crosslinking between hydrophilic groups -A2 and/orhydrophobic groups -A1- of adjacent molecules.

EMBODIMENT 4

An optical component having a crosslinked anti-fog coating obtainable bycovalent attachment of a silane derivative of the formula (2) to thesurface of the optical component and crosslinking of adjacent molecules:

R_(o)X_(m)SiB_(n)  (2)

wherein

m=1 to 3, n=1 or 2 and o=0 or 1, with the proviso that m+n+o=4;

the radical X is selected from halogen or C₁₋₄-alkoxy, and for m=2 or 3the individual radicals X may be identical or different,

the radical R is C₁-₄-alkyl,

the radical B has the structure -B1-B2, in which -B2 is a terminalhydrophilic group which is crosslinked to at least one hydrophilic groupof an adjacent molecule of the anti-fog coat, and -B1- represents eithera spacer group, which joins the hydrophilic group B2 to the Si atom, ora covalent bond,

where the terminal hydrophilic group -B2 is poly(meth)acrylate,

and for n=2 the individual radicals B may be identical or different,

and where the poly(meth)acrylate of the terminal hydrophilic group -B2comprises monomer units which are selected from CH₂═C(CH₃)COOH₁₋₄-alkyl,CH₂═C(H)COOCH₁₋₄-alkyl, hydroxyethylene methacrylate,2-acrylamido-2-methylpropanesulphonic acid, trimethylolpropanetriacrylate and pentaerythritol tetraacrylate or mixtures thereof.

EMBODIMENT 5

The optical component according to Embodiment 1, where the covalentattachment of the compound of the formula (1) to the surface of theoptical component takes place by reacting at least one of the reactive—Si—X— groups with a suitable reactive surface group to form —Si—O—.

EMBODIMENT 6

The optical component according to Embodiment 1, where the opticalcomponent comprises an anti-reflection coat and the anti-fog coating isapplied to the anti-reflection coat.

EMBODIMENT 7

A method for producing a crosslinked anti-fog coating on an opticalcomponent comprising:

-   -   covalently bonding a precursor compound to the surface of the        optical component, the precursor compound having the formula        (3):

R_(o)X_(m)SiC_(n)  (3)

wherein

m=1 to 3, n=1 or 2 and o=0 or 1, with the proviso that m+n+o=4,

the radical X is selected from halogen or C₁-₄-alkoxy, and for m=2 or 3the individual radicals X may be identical or different,

the radical R is C₁₋₄-alkyl,

the radical C has the structure -C1-C2, in which -C2 is a teiminal grouphaving a (meth)acrylate functionality and -C1- represents either aspacer group or a covalent bond;

-   -   reacting the terminal group -C2 with (meth)acrylate monomers to        give a hydrophilic poly(meth)acrylate group; and,    -   crosslinking of the hydrophilic poly(meth)acrylate groups of        adjacent molecules.

EMBODIMENT 8

A method for producing a crosslinked anti-fog coating on an opticalcomponent according to Embodiment 4, comprising:

-   -   providing the optical component and the covalent attachment of        the silane derivative of the formula (2) by chemical reaction        with reactive groups on the surface of the optical component,        followed by the crosslinking of the hydrophilic groups -B2 of        adjacent molecules of the anti-fog coating.

EMBODIMENT 9

A method for producing an anti-fog coating on an optical component,according to Embodiment 1, comprising:

-   -   providing of the optical component and the covalent attachment        of the silane derivative of the formula (1) by chemical reaction        with reactive groups on the surface of the optical component.

EMBODIMENT 10

The optical component according to Embodiment 4, where the covalentattachment of the compound of the formula (2) to the surface of theoptical component takes place by reacting at least one of the reactive—Si—X— groups with a suitable reactive surface group to form —Si—O—.

EMBODIMENT 11

The optical component according to Embodiment 6, where the anti-fogcoating having a coat thickness of 100 nm or less.

The invention is described in further detail by the following examples:

EXAMPLES Example 1

A polyethylene glycol (PEG) modified trichlorosilane (Mn˜500 g/mol) isdissolved in toluene so that a 5 mass % solution is obtained. A glasshaving an antireflective coating but no CleanCoat is dipped into thesolution and then air-dried. Any remaining over-coating is removed byrubbing with a dry cloth.

Example 2

A polyethylene glycol (PEG) modified trichlorosilane (Mn˜500 g/mol) isdissolved in toluene so that a 2.5 mass % solution is obtained. A glasshaving an antireflective coating but no CleanCoat is dipped into thesolution and then air-dried. Any remaining over-coating is removed byrubbing with a dry cloth.

By covalently attaching the PEG-modified silane to the substratesurface, coatings are obtained in Examples 1 and 2 which provideanti-fogging properties. Due to the higher concentration of thePEG-modified silane, the anti-fogging effect provided in Example 1 ishigher than in Example 2.

Example 3

9.98 g 3-methacryloxypropyl trichlorosilane are dissolved in 490 mltoluene. A glass is stored in said solution for one hour and thenair-dried. In a second step, the glass is dipped into a solution made of5.0 g 2-hydroxyethyl methacrylate (HEMA), 1.0 g trimethylolpropanetriacrylate (TMPTA) and 0.5 gdiphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide in 50 ml toluene,followed by curing with a Panacol UV-D-1000 lamp.

Example 4

10.01 g 3-methacryloxypropyl trichlorosilane are dissolved in 240 mltoluene. A glass having an antireflective coating is stored in saidsolution for one hour and then air-dried. In a second step, the glass isdipped into a solution made of 10.0 g 2-hydroxyethyl methacrylate(HEMA), 3.0 g trimethylol propanetriacrylate (TMPTA) and 0.5 gdiphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide in 100 ml toluene,followed by curing with a Panacol UV-D-1000 lamp.

So, in Examples 3 and 4, a precursor compound having a terminalmethacrylate functionality is covalently attached to the substratesurface in a first step, followed by a second step which includes achemical reaction with further (meth)acrylate monomers so as to obtainthe terminal poly(meth)acrylate group, and a crosslinking ofneighbouring molecules.

The coatings prepared in Examples 3 and 4 both provide an antifoggingeffect.

A higher percentage of the monomer hydroxyethyl methacrylate increasesthe hydrophilic character of the coating and thereby its antifoggingeffect, whereas a higher percentage of the monomer trimethylolpropanetriacrylate increases the crosslinking within the coating and therebyimproves mechanical properties.

It is understood that the foregoing description is that of the preferredembodiments of the invention and that various changes and modificationsmay be made thereto without departing from the spirit and scope of theinvention as defined in the appended claims.

1-11. (canceled)
 12. An optical component having a crosslinked anti-fogcoating obtainable by covalent attachment of a silane derivative of theformula (2) to the surface of the optical component and crosslinking ofadjacent molecules:R_(o)X_(m)SiB_(n)  (2) wherein m=1 to 3, n=1 or 2 and o=0 or 1, with theproviso that m+n+o=4; the radical X is selected from halogen orC₁₋₄-alkoxy, and for m=2 or 3 the individual radicals X may be identicalor different, the radical R is C₁₋₄-alkyl, the radical B has thestructure -B1-B2, in which -B2 is a terminal hydrophilic group which iscrosslinked to at least one hydrophilic group of an adjacent molecule ofthe anti-fog coat, and -B1- represents either a spacer group, whichjoins the hydrophilic group B2 to the Si atom, or a covalent bond wherethe terminal hydrophilic group -B2 is poly(meth)acrylate, and for n=2the individual radicals B may be identical or different.
 13. The opticalcomponent according to claim 12, where the covalent attachment of thecompound of the formula (2) to the surface of the optical componenttakes place by reacting at least one of the reactive —Si—X— groups witha suitable reactive surface group to form —Si—O—.
 14. The opticalcomponent according to claim 12, where the optical component comprisesan anti-reflection coat and the anti-fog coating is applied to theanti-reflection coat.
 15. The optical component according to claim 12,wherein the anti-fog coating having a coat thickness of 100 nm or less.16. The optical component according to claim 12, wherein thepoly(meth)acrylate of the terminal hydrophilic group -B2 comprisesmonomer units which are selected from CH₂═C(CH₃)COOC₁₋₄-alkyl,CH₂═C(H)COOC₁₋₄-alkyl, hydroxyethylene methacrylate,2-acrylamido-2-methylpropanesulphonic acid, trimethylolpropanetriacrylate and pentaerythritol tetraacrylate or mixtures thereof.
 17. Amethod for producing a crosslinked anti-fog coating on an opticalcomponent comprising: covalently bonding a precursor compound to thesurface of the optical component, the precursor compound having theformula (3):R_(o)X_(m)SiC_(n)  (3) wherein m=1 to 3, n=1 or 2 and o=0 or 1, with theproviso that m+n+o=4, the radical X is selected from halogen orC₁₋₄-alkoxy, and for m=2 or 3 the individual radicals X may be identicalor different, the radical R is C₁₋₄-alkyl, the radical C has thestructure -C1-C2, in which -C2 is a terminal group having a(meth)acrylate functionality and -C1- represents either a spacer groupor a covalent bond; reacting the terminal group -C2 with (meth)acrylatemonomers to give a hydrophilic poly(meth)acrylate group; and,crosslinking of the hydrophilic poly(meth)acrylate groups of adjacentmolecules.
 18. A method for producing a crosslinked anti-fog coating onan optical component according to claim 12, comprising: providing theoptical component and the covalent attachment of the silane derivativeof the formula (2) by chemical reaction with reactive groups on thesurface of the optical component, followed by the crosslinking of thehydrophilic groups B2 of adjacent molecules of the anti-fog coating. 19.The method according to claim 17, wherein the (meth)acrylate monomersare selected from the group consisting of CH₂═C(CH₃)COOC₁₋₄-alkyl,CH₂═C(H)COOC₁₋₄-alkyl, hydroxyethylene methacrylate,2-acrylamido-2-methylpropanesulphonic acid, trimethylolpropanetriacrylate and pentaerythritol tetraacrylate or mixtures thereof.